1. Field of the Invention
The present invention is directed to a radioshielded assembly having components that require a d.c. supply and having multi-pole terminal means that are connected, between power supply terminals of the components and fashioned an external d.c. power supply, with at least one pole of the multi-pole terminal means being fashioned for conducting a potential that differs from a reference potential.
2. Description of the Prior Art
Electronic assemblies that are operated in radiofrequency measuring chambers require special radioshielding measures in order to avoid an influence of alternating electromagnetic fields on the actual measuring system in the measuring compartment. One such measure is to dispose the power supply for the assembly outside the radiofrequency measuring chamber and power is supplied to the assembly as a d.c. voltage or current. When, however, the electrical power consumed by the assembly is so high in the radiofrequency range that the radiofrequency measuring system operated in the measuring chamber could be disturbed, then the power supply lines must also be radioshielded. These measures, however, can still be inadequate under certain circumstances. When, for example, an LCD monitor having a high resolution of 1024xc3x971280 points and an image or frame repetition rate of 60 Hz is to be operated inside a nuclear magnetic resonance measuring chamber, even a shielding of the d.c. leads can be inadequate.
It is an object of the present invention to provide a radioshielded assembly wherein radiofrequency interference emanating from the power leads is suppressed.
This object is achieved in a radioshielded assembly of the type initially described wherein a switch is inserted between that pole of the terminal means that does not carry reference potential and the corresponding power supply terminals of the components with an actuation means in interactive communication with the switch which permit the connected pole to be electrically connected to the power supply terminals or to be disconnected from the power supply terminals and electrically connected to a reference potential and wherein an arrangement of electrochemical elements is connected in parallel with the power supply terminals. The disconnection of the assembly from the external power supply ensues only during the measuring mode in the radiofrequency measuring chamber, while the assembly continues to be supplied with electrical energy via the electrochemical elements in the form of a battery or rechargeable accumulator. The assembly can be connected to the external power supply during measuring pauses.
In one embodiment a switch is inserted between each pole of the terminal means and between the corresponding power supply terminals of the components and the actuation means is in interactive communication with the switch, as a result of which the connected poles can be connected to the corresponding power supply terminals or the poles can be disconnected from the power supply terminals and electrically connected to a reference potential. The disconnection of all poles from the external power supply and the limitation of the power supply lines in terms of potential suppresses the radiofrequency interference emanating from the reference potential lead, even though this interference is only slight.
When the assembly itself emits radiofrequency interference to a noteworthy extent, the disturbing effects can be suppressed according to a further embodiment wherein at least one component, namely the interfering component, is surrounded by a shielding that lies at reference potential.
An automatic switching at the assembly can ensue according to another embodiment wherein the actuation means are formed by a relay coil.
The relay coil can be electrically connected to the multi-pole terminal means and power supply lines can be connected to the e multi-pole terminal means, and a control contact for the actuation of the relay coil can be inserted into at least one of the lines connected to the relay coil. A separate control line for the relay coil can thus be foregone.
In another embodiment secondary elements are utilized as the electrochemical elements. The secondary elements can be recharged by the external power supply during pauses in the operation of the radiofrequency measuring system.